I have. I just sold my Grumman. I placed a review that I thought it was better than the superdown pro, but after more use last winter I think the pro is loftier over time and much more durable. Every time I put the grumman on I lost a feather or two. If your going to rock the Grumman you mine as well get an arcteryx jacket or Rab or something similar. The fabric shell makes a huge difference for warmth in my opinion.
Depending on hunting style or location neither maybe warm enough for late season glassing. You can resell a super down pro with a 20-30 percent loss margin. That goes down if you use a kuiu coupon bday code. The same resell margin applies to the grumman. If you have the money I'd buy a couple jackets and test each and resell one next year, or buy both on paypal credit and send back whichever you like least for a refund.
When it comes to down jackets I would buy one from a mountaineering company if I can only have 1.